In the medical field, medical fluids or solutions are commonly administered to patients by intravenous (I.V.) techniques. The medical fluid is usually contained within an I.V. bag which is suspended above the patient by an I.V. pole. An I.V. tubing line connects the I.V. bag of medical fluid to the patient through an I.V. needle or catheter inserted into the patient's venous system. The medical fluid flows from the elevated I.V. bag into the patient due to the force of gravity. Medical fluids can also be administered to a patient by an I.V. infusion pump connected to an I.V. tubing line. Devices that utilize these types of I.V. administration techniques are termed I.V. administration sets.
Frequently, the rate in which the medical fluid is administered to the patient must be controlled to provide proper medical treatment. Accordingly, the medical fluid is administered to the patient over an extended period of time rather than being entirely infused into the patient immediately. Of course, various medical treatments and various medical fluids may require different rates of I.V. fluid administration. The rate of I.V. fluid administration is dependant, in part, on the fluid pressure in the I.V. administration set.
Various devices and techniques have been utilized to control fluid pressure in the I.V. administration set and the corresponding fluid flow rate of the medical fluid to the patient. A clamp, for example, may be placed on the I.V. tubing line to partially restrict the flow of fluid through the tubing. However, the clamping force applied by the clamp, the amount of tubing restriction, and the control of the fluid flow rate are subject to considerable variability. Another device which purports to control the rate of fluid flow is disclosed in U.S. Pat. No. 4,343,305 to Bron, titled ADJUSTABLE-RATE, CONSTANT OUTPUT INFUSION SET (the "Bron device").
The Bron device includes a connector piece, an inlet port, a control port, an annular member, and an elastic diaphragm. The annular member is made of a rigid, substantially non-deformable material and has a step-like recess. The annular member is mounted inside the connector piece such that the diaphragm is seated in the recess. The connector piece and the diaphragm form a first chamber in communication with a fluid container via the inlet port. The connector piece and the diaphragm further form a second chamber in communication with the control port. A fluid passageway, having a flow restriction, is provided from the first chamber to the second chamber. The diaphragm is movable between positions that are close to the control port, which reduce fluid flow, and positions that are further away from the control port, which increase fluid flow. Although the Bron device purports to control the rate of fluid flow, the Bron device exhibits problems in achieving that objective. Under certain conditions, the Bron device may not control the rate of fluid flow and instead allow the fluid to flow freely or substantially unrestricted through the device. The free flow state may occur when the diaphragm slips off or tucks under the step-like recess on the annular member. The diaphragm may slip off or tuck under at a localized area or over a substantial portion of the diaphragm. When the diaphragm slips off of or tucks under the recess, a relatively large, unrestricted free flow path may be created between the first chamber and the second chamber. The fluid will flow through the unrestricted free flow path instead of the restricted passageway. Accordingly, when the diaphragm slips off of or tucks under the recess, fluid may freely flow from the fluid container to the inlet port, to the first chamber, through the free flow path to the second chamber, to the control port and then, into the patient. Compounding the problem, after the diaphragm has slipped off of or tucked under the recess the diaphragm does not return to a proper seated position on the recess. Therefore, fluid may be infused into a patient at a free flow rate instead of a controlled, reduced rate.
In use of the Bron device, it has been found that a bolus injection of fluid by a syringe into the infusion set upstream of the device may cause the diaphragm to slip off of or tuck under the annular member recess. Although medical personnel had been advised to administer bolus injections only downstream of the device, sometimes forceful, repeated upstream bolus injections occurred. It has also been found that excessive fluid container pressure may cause the diaphragm to slip off of or tuck under the annular member recess.
Therefore, a need exists to improve intravenous fluid flow regulators. Particularly, a need exists to improve intravenous fluid flow regulators by preventing fluid free flow conditions. The present invention satisfies this need. The present invention improves fluid flow regulators by providing regulators that prevent a diaphragm from slipping off of or tucking under a diaphragm holder.
Accordingly, one advantage of the present invention is to improve intravenous fluid flow regulators.
Another advantage of the present invention is to prevent fluid free flow conditions through the flow regulator.
Another advantage of the present invention is to provide a flow regulator that is resistant to misuse such as administration of bolus injections upstream of the flow regulator.
Another advantage of the present invention is to prevent a flexible diaphragm from slipping off of or tucking under a diaphragm holder.
Additional advantages of the present invention will be apparent from reviewing this specification, the drawings, and the claims.